Avalanche forecast

East Slopes South

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

A winter storm with strong winds will bring increasing avalanche danger on Saturday night into Sunday. Winds will transport this new snow into deep drifts on the lee side of ridgelines at upper elevations. Travel around steep terrain where you see large pillowlike drifts or actively blowing snow. Exposed rocks, stumps, and other hazards can increase the consequences of being caught in even a small avalanche. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    The incoming storm will likely favor the northern and western Cascades, and the East South zone may only pick up 4-6" of new snow. However, ridgeline winds in the 30-40mph range will easily transport this new snow into deeper slabs on the lee side of ridges. Since many areas still have a thin snowpack, you will most likely encounter these unstable slabs on steep ridgelines with little vegetation or trees. Use visual clues such as cornices, textured surfaces, or wind drifts to identify wind loaded terrain. Watch for signs of instability, such as cracks shooting out from your skis, snow that sounds hollow, and actively blowing snow. If you encounter any of these signs, move to lower angle or sheltered terrain. 

    There may be elevated hazard in areas of the zone closer to the Cascade Crest, which is forecasted to receive significantly more snow. If you are traveling in areas near the west side of Rimrock Lake or Bumping Lake, check out the West South Forecast.

    An example of a cornice and wind feature indicating wind direction from right to left in this image. 

    Photo: Josh Hirshberg

Avalanche Discussion

Access to many areas of the eastern Cascades is challenging, and we have limited information about the snowpack. This storm will likely begin as rain for locations below 3500ft, and with just a few inches of new snow anticipated for lower elevation trailheads, access will remain challenging. If you are headed out into the mountains this weekend, be prepared for long approaches on nearly bare ground. Many motorized trailheads have limited snowpack, and most have yet to begin grooming operations. New snow may shallowly bury rocks, stumps, creeks, or other hazards at upper elevations. 

Many areas on the eastern slopes of the Cascades enjoyed an early start to winter at the beginning of November, receiving 8-10" of snow down to valley bottoms. Prolonged, cold, dry weather followed this storm, transforming this snow into weak, angular, sugary snow crystals. We received observations of surface hoar growth and weak snow in the Mt. Aix and Darland Mountain areas. This weak layer may now be buried up to 15" in some locations. This past week's warm temperatures have helped to strengthen and round these snow grains, and an NWAC forecaster found a strong and well settled snowpack at nearby Crystal Mountain. However, we still have some uncertainty about the extent and distribution of this weak snow layer. When traveling on sheltered northern aspects, it is important to dig down and determine if this persistent weak layer exists beneath the new snow. Avoid traveling on steep terrain if you find a weak sugary layer of snow or feel the snowpack collapse beneath you. 

If you take advantage of the fresh snow on Saturday, let us know what you find by submitting an observation.

Regions covered